Neon tetra help

[Fishtank]

Had these fish for nearly 5 years now I think. This particular fish has always had an internal bump inside the end of his tail before the fin. Hes always eaten well and swam fine etc. Woke up today to find hes on his way out and it looks like whatever growth has been hidden inside his body all these years has burst forth any ideas on what it could be?

[plankton]

That just looks like old age to me.

[Art]

It looks like Pleistophora to me. The light spot in the red area.

[plankton]

It's possible I suppose, but from the rest of the fish it looks like the colour is fading all over and the bending spine is a sign of an ancient fish.

[Art]

Yes, by the age of 5, neon is old enough.
It's just because of the contagion.